General: Silence modules on (un)load.

General: Silence modules on (un)load.

Some (normally optional) modules created notices, warnings, and even errors
in normal situations like (un)load. This cluttered the command-line interface
(CLI) on start and while stopping gracefully. However, when an user went for
the script './contrib/scripts/install_prereq', those modules get compiled-in
because their prerequisites were met at compile time. Furthermore, because of
ASTERISK_27475, the former talkative module 'res_curl' is built as side-effect.

ASTERISK-27553

Change-Id: I9f105f46d72553994e820679bfde3478a551b281